A liquid crystal display (LCD) is a display device to display desired images by adjusting transmittance of light passing through pixels by individually supplying data signals according to image information to the pixels aligned in the form of a matrix. Since the LCD is a non-emissive device, a backlight unit is installed at a rear of the LCD to display the images.
The backlight unit has a function of uniformly supplying light to a rear surface of the non-emissive LCD to display the images and includes a light guide member having a function of uniformly distributing the brightness and the light of the backlight unit. The light guide member is one of plastic lenses for uniformly transferring the light emitted from a light emitting diode (LED) to the LCD.
FIG. 1 is a sectional view showing the structure of a backlight unit employing the LED as a light source. As shown in FIG. 1, the backlight unit includes a plurality of LEDs 20 installed on a printed circuit board 10 and a light guide member 30 for transferring the light emitted from the LEDs 20 in the upward direction. In particular, recently, there are many attempts to uniformly emit the light through the entire light emitting surface by using a plurality of LEDs. In this case, the LEDs are aligned on a plane and concave holes are formed in the guide member such that the LEDs can be inserted into the concave holes.
However, if the LEDs are inserted into the concave holes, a hot spot may occur at the surface adjacent to the LEDs due to the heat, so the brightness may become relatively high at the surface adjacent to the LEDs, resulting in the brightness blot. In addition, as shown in FIG. 1, if edges E having a predetermined angle are formed at the concave holes receiving the LEDs, the light emitted to the edges may be reflected or irregularly travelled, so that the light characteristics may be degraded.